Statistical analysis
Statistical analyses were performed using SPSS v.22 (IBM Corp., Armonk, NY, USA). To investigate differences in sleep quality, insomnia, and psychological symptoms between AD and healthy adults, the questionnaire scores (PSQI, ISI, BDI-II, GAD-7, PSS-10) of the two groups (Atopic Dermatitis, Control) were compared using the independent samples t-Test. Cohen’s d was computed to provide an effect size estimate of the comparisons between groups.
We estimated the influence of objective and subjective severity of AD on sleep quality and insomnia by performing several univariable linear regression analyses, with EASI and POEM scores as independent variables and PSQI and ISI scores as dependent variables.
Similarly, we performed univariable linear regression analyses to test if objective (EASI) and self-perceived (POEM) severity of AD (independent variables) significantly predicted depression (BDI-II), anxiety (GAD-7), and self-perceived stress (PSS-10; dependent variables). The level of significance was set at p < 0.05, and all analyses were two-tailed.